Abstract:

A wheel bearing apparatus incorporating a wheel speed detecting apparatus
has a wheel bearing with an outer member and an inner member. A sensor
holder is injection molded from synthetic resin and is embedded with a
wheel speed detecting sensor. The sensor holder is mounted on an inner
side end of the outer member. The inner side seal of the seals includes
an annular sealing plate, a slinger and a pulser ring. An anchoring
portion is formed integrally with the metal core. The sensor holder is
being integrally molded with the metal core from synthetic resin that
surrounds the anchoring portion

Claims:

1. A wheel bearing apparatus incorporating a wheel speed detecting
apparatus comprising:an outer member integrally formed with a body
mounting flange on its outer circumference, said body mounting flange to
be mounted on a suspension apparatus of a vehicle, and said outer member
inner circumference includes double row outer raceway surfaces;an inner
member including a wheel hub and at least one inner ring, the wheel hub
having, at one end, an integrally formed wheel mounting flange, said
wheel hub outer circumference including an inner raceway surface, a
cylindrical portion axially extending from the inner raceway surface, the
inner ring being fit onto the cylindrical portion of the wheel hub, the
inner ring being formed with the other inner raceway surface on its outer
circumference, the other inner raceway surfaces arranged opposite to the
double row outer raceway surfaces;double row rolling elements are freely
rollably contained between the inner and outer raceway surfaces,
respectively, of the inner member and the outer member;seals are mounted
in annular openings formed between the outer member and the inner
member;a sensor holder is injection molded from a synthetic resin, a
wheel speed detecting sensor is embedded in said sensor holder, said
sensor holder is mounted on an inner side end of the outer member;the
inner side seal of the seals including an annular sealing plate, a
slinger and a pulser ring, the slinger has a substantially L-shaped
cross-section and is mounted onto the outer circumference of the inner
ring, the pulser ring is fit onto the outer circumference of the slinger,
the pulser ring includes a magnetic encoder with circumferential
characteristics that alternately and equidistantly change;the sealing
plate includes a metal core press formed from a steel plate, the sealing
plate is insert molded into the sensor holder and includes an exposed
portion of the metal core that is into the end portion of the outer
member, a sealing member is integrally bonded to the metal core, the seal
member has integrally formed side lips and radial lips;the side lips of
the sealing member are in sliding contact with the slinger and/or the
pulser ring;the magnetic encoder and a wheel speed sensor are arranged
opposite each other via a radial gap;an anchoring portion is integrally
formed with the metal core and the sensor holder integrally molded with
the metal core from synthetic resin surrounding the anchoring portion.

2. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 1, wherein the metal core includes an outer
cylindrical portion press-fit into the end portion of the outer member, a
standing portion extends radially inward from the outer cylindrical
portion, an inner cylindrical portion axially extends toward the inner
side, and a radially inner portion extends radially inward from the inner
cylindrical portion, the sealing member is integrally adhered to the
radially inner portion, and the anchoring portion is a tongue formed by
folding an end portion of the outer cylindrical portion radially outward.

3. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 1, wherein the anchoring portion is a circular
aperture formed in the metal core.

4. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 3 wherein a plurality of the circular aperture are
formed in the outer cylindrical portion of the metal core along its
circumference.

5. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 3 wherein a plurality of the circular aperture are
formed in the standing portion of the metal core along its circumference.

6. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 3 wherein a plurality of the circular aperture is
formed in the inner cylindrical portion of the metal core along its
circumference.

7. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 1, wherein the inner ring is formed with a smaller
diameter portion and a larger diameter portion, a cylindrical portion of
the slinger is press-fit onto the smaller diameter portion of the inner
ring, the pulser ring includes a supporting member and the magnetic
encoder, the supporting member is press-formed from ferromagnetic steel
plate and includes an inner cylindrical portion press-fit onto the
cylindrical portion of the slinger, a standing portion extending radially
outward from the inner cylindrical portion, and an outer cylindrical
portion, formed with a slightly larger diameter than the larger diameter
portion of the inner ring, has the magnetic encoder adhered to the outer
cylindrical portion of the supporting member, the magnetic encoder is
formed from an elastomer mingled with magnetic powder, the encoder has N
and S poles alternately arranged along its circumference, the encoder is
arranged opposite to the wheel speed sensor via a radial gap relative to
the inner cylindrical portion of the metal core without contact.

9. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 7, wherein the supporting member is press-formed from
ferromagnetic steel plate and the magnetic encoder is formed from an
elastomer mingled with magnetic powder, the magnetic encoder has N and S
poles alternately arranged along its circumference.

10. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 1, wherein a disc shaped cover is arranged at the
inner side of the sensor holder, an inner circumference of the disc
shaped cover is arranged opposite to the outer circumference of a
shoulder of an outer joint member via a small radial gap to form a
labyrinth seal therebetween, and drains are formed on or near the inner
circumference of the disc shaped cover.

11. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 10, wherein the drains are circular apertures formed
equidistantly along the inner circumference of the disc shaped cover.

12. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 10 wherein the drains are notches formed equidistantly
along the inner circumference of the disc shaped cover.

13. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 10 wherein a diameter A of the inner circumference of
the disc shaped cover is set within a range B+D≦A≦C-D;
wherein B is an outer diameter of the shoulder of the outer joint member,
C is an outer diameter of the slinger, and D is an axial gap between the
disc shaped cover and the slinger.

14. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 13 wherein the shoulder abuts against a larger end
face of the inner ring, the outer diameter of the shoulder is set smaller
than that of the inner ring, and wherein an elastic lip is integrally
adhered to the slinger and contacts the end face of the inner ring.

15. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 10, wherein the slinger and the disc shaped cover are
press-formed from steel plate having preserving ability.

16. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 1, wherein the minimum anti-pull out force of the
sensor holder relative to the outer member is defined by a formula
Fmin=m×a, wherein "m" is mass of the sensor holder, and "a" is a
vibration acceleration, and the anti-pull out force of the sensor holder
is set at Fmin or more.

17. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 1, wherein a connector portion is integrally formed
with a portion of the sensor holder for mounting a harness connecting a
control means, mounted on a body of a vehicle, and the magnetic sensor,
an output signal from the magnet sensor can be sent to the control means
via a plug inserted into the connector portion, and the anti-pull out
force of the sensor holder relative to the connector portion and the plug
and relative to the outer member is set larger than the self-weight of
the wheel bearing apparatus.

18. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 17, wherein the connector portion is formed with a
locking projection projecting axially from the wheel bearing apparatus,
and the locking projection is formed with an inclined taper toward a plug
inserting direction so that the locking projection can be fit into a
recess formed in the plug and locked therein.

19. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 16, wherein the fitting interface between the outer
member and the metal core can be adjusted based on the anti-pull out
force of the sensor holder.

20. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 1, wherein the metal core includes an outer
cylindrical portion press-fit into the end portion of the outer member, a
standing portion extending radially inward from the inner side end of the
outer cylindrical portion, an inner cylindrical portion axially extending
toward the outer side from the standing portion, and a radially inner
portion extending radially inward from the inner cylindrical portion, the
sensor holder is integrated with the metal core and is insert molded in a
region including the outer cylindrical portion, the standing portion and
the inner cylindrical portion, and the sealing member is adhered to the
radially inner portion and is arranged to the inner side from the
detecting portion of the wheel speed sensor.

21. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 20, wherein the magnetic encoder is formed of an
elastomer such as a rubber magnet mingled with magnetic powder, the
magnetic encoder has N and S poles alternately arranged along its
circumference, the wheel speed sensor includes a magnetic detecting
element, varying its characteristics in accordance with the flow
direction of magnetic flux, and an IC, the IC is incorporated, via a lead
wire, with a wave forming circuit for rectifying the output wave form of
the magnetic detecting element, and an aperture enabling passage of the
lead wire is formed in the outer cylindrical portion of the metal core.

22. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 20, wherein a plurality of apertures is formed in the
outer cylindrical portion of the metal core.

24. The wheel bearing apparatus incorporating a wheel speed detecting
apparatus of claim 20, wherein an annular groove is formed on the inner
circumferential surface at the inner side end of the outer member, and a
radially outwardly deformed engaging portion is formed at the outer side
end of the outer cylindrical portion of the metal core so that it is fit
in the annular groove.

[0002]The present disclosure relates to a wheel bearing apparatus
incorporating a wheel speed detecting apparatus to detect a rotation
speed of a wheel of a vehicle.

BACKGROUND

[0003]A wheel bearing apparatus that supports a wheel of a vehicle
relative to a suspension apparatus and that incorporates a wheel speed
detecting apparatus to detect a rotational speed of a wheel of a vehicle
to control the anti-lock braking system (ABS) is generally known. Such a
bearing apparatus generally includes a sealing apparatus between an inner
member and an outer member. The inner and outer members are rotatable
relatively to each other via rolling elements (balls) between the two. A
magnetic encoder has alternately arranged magnetic poles along its
circumference and is integrated into the sealing apparatus. A wheel speed
detecting sensor detects the variation in magnetic poles of the magnetic
encoder according to the rotation of the wheel.

[0004]The wheel speed sensor is usually mounted on a knuckle after the
wheel bearing apparatus is mounted on the knuckle to form a suspension
apparatus. Recently, however, a wheel bearing apparatus incorporating a
wheel speed detecting apparatus has been proposed where the wheel speed
detecting sensor is self-contained within the wheel bearing. This reduces
the size of the wheel bearing apparatus as well as eliminates troublesome
in air gap adjustment between the wheel speed sensor and the magnetic
encoder.

[0005]An example of a prior art wheel bearing apparatus incorporating a
wheel speed detecting apparatus is shown in FIG. 15. This wheel bearing
apparatus incorporating a wheel speed detecting apparatus 100 includes an
outer member 101, an inner member 103, inserted into the outer member via
double row balls 102, and a wheel speed detecting apparatus 104, mounted
on one end of the outer member.

[0006]The outer member 101 is integrally formed with a body mounting
flange on its outer circumference. The body mounting flange 101b is to be
mounted on a knuckle (not shown) to form a portion of a suspension of a
vehicle. The outer member inner circumference includes double row outer
raceway surfaces 101a, 101a.

[0007]The inner member 103 includes a wheel hub 105 and an inner ring 106
secured on the wheel hub 105. The wheel hub 105 is formed at one end with
a wheel mounting flange 107 to mount a wheel (not shown). The wheel hub
outer circumference has one inner raceway surface 105a that oppose one of
the double row outer raceway surfaces 101a, 101a. A cylindrical portion
105b extends from the inner raceway surface 105a. The inner ring 106 is
formed with the other inner raceway surfaces 106a on its outer
circumference. The other inner raceway surface 106a opposes the other of
the double row outer raceway surfaces 101a, 101a. The inner ring 106 is
press-fit onto the cylindrical portion 105b of the wheel hub 105 via a
predetermined interface.

[0008]Double row balls 102, 102 are contained between the double row outer
raceway surfaces 101a, 101a and the inner raceway surface 105a, 106a,
respectively, of the wheel hub 105 and the inner ring 106. The balls 102,
102 are rollably held by cages 108, 108. In addition, seals 109, 110 are
mounted in annular openings formed between the outer member 101 and the
inner member 103. The seals 109, 110 prevent leakage of grease contained
in the bearing and entry of rainwater or dusts from the outside.

[0009]The wheel speed detecting apparatus 104, as shown in FIG. 16,
includes a sensor holder 112 with an embedded magnetic sensor 111 and a
seal 110. The sensor holder 112 is insert-molded to a metal core 115
forming the seal 110 by injection molding of synthetic resin.

[0010]The seal 110 is formed by a combination of a first seal ring 113 and
a second seal ring 114. The first seal ring 113 includes a metal core
115, formed of a rigid ring, and a sealing member 116 mounted on the
metal core 115. The metal core 115 has a cylindrical portion 115a to be
fit into the end of the outer member 101. An outer flange portion 115b
extends radially inward from the cylindrical portion 115a. A cylindrical
portion 115c, that prevents entry of water, extends axially toward the
inner side from the flange portion. An inner flange portion 115d extends
radially inward from the cylindrical portion 115c. A sealing member 116
is adhered on the inner circumference of the inner flange portion 115d.

[0011]The second seal ring 114 includes a slinger 117, with a
substantially L shaped cross-section, mounted onto the inner ring 106,
and a pulser ring 118, fit onto the slinger 117. The slinger 117 has a
cylindrical portion 117a press-fit onto a smaller diameter portion 106b
of the inner ring 106. A flange portion 117b extends radially outward
from the cylindrical portion 117a. An elastic seal 119 is mounted on the
cylindrical portion 117a of the slinger 117. The elastic seal 119 has an
axial lip 119a in sliding contact with the end face of the inner ring
106.

[0012]The pulser ring 118 includes an annular supporting member 120 and a
magnetized member 121. The supporting member 120 has a smaller
cylindrical portion 120a press-fit onto the cylindrical portion 117a of
the slinger 117. A connecting portion 120b extends radially outward from
the smaller cylindrical portion 120a. A larger cylindrical portion 120c,
extending from the connecting portion 120b, is fit onto the larger
diameter portion 106c of the inner ring 106. The magnetized member 121 is
adhered to the larger cylindrical portion 120c. The magnetized member 121
is made of rubber or synthetic resin mingled with magnetic powder. N and
S poles are alternately arranged along the magnetized member 121. The
magnetized member 121 is arranged opposite to the magnetic sensor 111 so
that it does not contact the cylindrical portion 115c of the metal core
115.

[0013]The sealing member 116 includes a side lip 116a, a pair of radial
lips 116b, 116c and a side lip 116d. The side lip 116a of the slinger
side slidingly contacts the flange portion 117b of the slinger 117. The
pair of radial lips 116b, 116c slidingly contacts the smaller cylindrical
portion 120a of the supporting member 120. The side lip 116d of the
pulser side slidingly contacts the connecting portion 120b of the
supporting member 120.

[0014]The sensor holder 112 is arranged opposite to the end face of the
outer member 101. An annular recess 122 is formed to expose a portion of
the cylindrical portion 115a of the metal core 115. O ring 123 is
elastically mounted within the recess 122. A disc shaped cover 124,
formed with an aperture having a diameter smaller than that of the
slinger 117, is mounted on the inner side end face of the sensor holder
112.

[0015]The entire structure including the O ring 123 of the wheel speed
detecting apparatus 104 can be previously assembled by first combining
the first seal ring 113 and the pulser ring 118. The supporting member
120 of the pulser ring 118 is then press fit onto the slinger 117. This
sub-assembly is axially pushed so that the cylindrical portion 115a of
the metal core 115 is fit into the outer member 101. The cylindrical
portion 117a of the slinger 117 is simultaneously press-fit onto the
smaller diameter portion 106b of the inner ring 106. Such a structure
makes it possible to prevent separation between the metal core 115 and
the sensor holder 112 as well as the entry of water from the interface
between the metal core 115 and the sensor holder 112. Reference Patent
Document: No. 183701/2006.

[0016]However, in the prior art wheel bearing apparatus 100 incorporating
a wheel speed detecting apparatus 104, it is believed that the synthetic
resin insert molded sensor holder 112 would separate from the metal core
115 that forms the first seal ring 113 when the wheel bearing apparatus
is used under severe running circumstances such as subjected to splashes
of muddy water or salty water or repeated high or low temperature. The
separation between the metal core 115 and the sensor holder 112 causes
variation in the air gap between the magnetic sensor 111 and the
magnetized member 121. Thus, this makes exact speed detection impossible.

[0017]Also in the prior art wheel bearing apparatus 100, even though the
wheel speed detecting apparatus 104 is protected by the disc shaped cover
124 mounted on the sensor holder 112 and the detecting portion is sealed
by the seal 110, it is believed that muddy water will solidify on the
slide contacting portion of the seal 110. This causes abnormal wear of
the sealing member 116 when muddy water enters over the disc shaped cover
124 and dwells in the seal 110. This detracts from the sealing
performance. Thus, it is difficult to assure the reliability of the
bearing for a long term.

[0018]In addition in the prior art wheel bearing apparatus 100, the sensor
holder 112 is displaced from the outer member 101 when it is used under
conditions where shock or vibration is applied to the apparatus 100. This
would not only detract from the sealability of the fitting portions and
the seal 110 but makes exact detection of the wheel speed impossible. The
sensor holder 112 with the metal core 115 is fit into the outer member
101. The metal core is in with metal-to-metal contact. Thus, the fitting
strength will be increased by improving the surface roughness and
dimensional accuracy of the fitting portion. However improvement of the
surface roughness and dimensional accuracy of the fitting portion also
increases the number of manufacturing steps and management steps and thus
reduces the cost effectiveness.

[0019]In the prior art wheel bearing apparatus 100, a connector portion
112a, for a harness (not shown) connecting the magnetic sensor 111 and a
control means (not shown) mounted on a body of the vehicle, is integrally
molded with the annular sensor holder 112 at a lower portion. Thus,
output signals from the magnetic sensor 111 are sent to the control means
by connecting a plug of the harness to the connector portion 112a.

[0020]During mounting of the wheel bearing apparatus 100 to a vehicle
after the wheel speed detecting apparatus 104 has been mounted on the
outer member 101, the wheel bearing apparatus 100 might be erroneously
handled and hung from the connector portion via the harness. It is
believed that such a handling of the wheel bearing apparatus 100 would
cause the plug to be dislodged from the connector 112a. Additionally, the
antilock braking system could not operate normally. Further, the sensor
holder 112 would be dislodged from the outer member 101 if the metal core
115 mounted on the outer member 101 is displaced.

[0021]Finally in the prior art wheel bearing apparatus 100, the magnetic
sensor 111 and the magnetized member 121 are oppositely arranged via the
cylindrical portion 115c of the metal core 115. Thus, it is difficult to
obtain high detecting accuracy and reliability. The detecting accuracy
and reliability are detracted by the presence of the metal core between
the magnetic sensor and the magnetized member.

SUMMARY

[0022]Therefore, it is an object of the present disclosure to provide a
wheel bearing apparatus incorporating a wheel speed detecting apparatus
that improves adhessiveness or integration between the plastic resin
sensor holder and the metal core and prevents detraction of the detecting
accuracy caused by separation between the sensor holder and the metal
core. Another object is to assure sealability and improve the reliability
of the wheel bearing apparatus.

[0023]A further object is to assure the anti-pull out force of the
connecting portion of harness and the sensor holder mounted on the outer
member, to improve the sealability of the fitting portions and the seal,
and to improve the detecting accuracy and reliability.

[0024]A wheel bearing apparatus incorporating a wheel speed detecting
apparatus comprises an outer member integrally formed with a body
mounting flange on its outer circumference. The body mounting flange is
to be mounted on a suspension apparatus of a vehicle. The outer member
inner circumference has double row outer raceway surfaces. An inner
member includes a wheel hub and at least one inner ring. The wheel hub
has an integrally formed wheel mounting flange at one end. The wheel hub
outer circumference includes an inner raceway surface opposing one of the
outer raceway surfaces. A cylindrical portion axially extends from the
inner raceway surface. The inner ring is fit onto the cylindrical portion
of the wheel hub. The inner ring is formed with the other inner raceway
surface on its outer circumference. The other inner raceway surface is
arranged opposite to the double row outer raceway surfaces. Double row
rolling elements are freely rollably contained between the inner and
outer raceway surfaces, respectively, of the inner member and the outer
member. Seals are mounted in annular openings formed between the outer
member and the inner member. A sensor holder is mounted on an inner side
end of the outer member. The sensor holder is injection molded of
synthetic resin and has an embedded wheel speed detecting sensor. The
inner side seal of the seals includes an annular sealing plate, a slinger
and a pulser ring. The slinger has a substantially L-shaped cross-section
and is mounted onto the outer circumference of the inner ring. The pulser
ring is fit onto the outer circumference of the slinger. The pulser ring
has a magnetic encoder with circumferential characteristics that
alternately and equidistantly change. The sealing plate includes a metal
core press formed from a steel plate. The sealing plate is insert-molded
into the sensor holder. An exposed portion of the metal core is fit into
the end portion of the outer member. A sealing member is integrally
bonded to the metal core. The sealing member has integrally formed side
lips and radial lips. The side lips of the sealing member are in sliding
contact with the slinger and/or the pulser ring. The magnetic encoder and
a wheel speed sensor are arranged opposite to each other via a radial
gap. An anchoring portion is integrally formed with the metal core. The
sensor holder is integrally molded with the metal core with synthetic
resin forming the sensor holder surrounding the anchoring portion.

[0025]Seals are mounted in annular openings formed between the outer
member and the inner member. A sensor holder, injection molded from
synthetic resin and embedded with a wheel speed detecting sensor, is
mounted on an inner side end of the outer member. The inner side seal of
the seals includes an annular sealing plate, a slinger and a pulser ring.
The slinger has a substantially L-shaped cross-section and is mounted
onto the outer circumference of the inner ring. The pulser ring is fit
onto the outer circumference of the slinger and has a magnetic encoder.
The magnetic encoder circumferential characteristics alternately and
equidistantly change. The sealing plate includes a metal core press
formed from a steel plate. The sealing plate is insert-molded into the
sensor holder. An exposed portion of the metal core is fit into the end
portion of the outer member. A sealing member is integrally bonded to the
metal core. The sealing member has integrally formed side lips and radial
lips. The side lips of the sealing member are in sliding contact with the
slinger and/or the pulser ring. The magnetic encoder and a wheel speed
sensor are arranged opposite to each other via a radial gap. An anchoring
portion is integrally formed with the metal core. The sensor holder is
integrally molded with the metal core with synthetic resin forming the
sensor holder surrounding the anchoring portion. Thus, it is possible to
assure the adhessiveness or integration between the plastic resin sensor
holder and the metal core even though the wheel bearing apparatus is used
under severe running circumstances subjected to splashes of muddy water
or salty water or repeated high temperatures and low temperatures.
Accordingly, it is possible to provide a wheel bearing apparatus
incorporating a wheel speed detecting apparatus that can prevent
separation between the plastic resin sensor holder and the metal core for
long term and also prevent detraction of the detecting accuracy caused by
the separation between the sensor holder and the metal core.

[0026]The metal core includes an outer cylindrical portion press-fit into
the end portion of the outer member. A standing portion extends radially
inward from the outer cylindrical portion. An inner cylindrical portion
axially extends toward the inner side. A radially inner portion extends
radially inward from the inner cylindrical portion. The sealing member is
integrally adhered to the radially inner portion. The anchoring portion
is a tongue formed by folding an end portion of the outer cylindrical
portion radially outward.

[0027]The anchoring portion is a circular aperture formed in the metal
core. A plurality of the circular aperture are formed in the outer
cylindrical portion of the metal core along its circumference. A
plurality of the circular aperture may be formed in the standing portion
of the metal core along its circumference. Furthermore, a plurality of
the circular aperture may be formed in the inner cylindrical portion of
the metal core along its circumference.

[0028]The inner ring is formed with a smaller diameter portion and a
larger diameter portion. A cylindrical portion of the slinger is
press-fit onto the smaller diameter portion of the inner ring. The pulser
ring includes a supporting member and the magnetic encoder. The
supporting member is press-formed from a ferromagnetic steel plate. The
supporting member includes an inner cylindrical portion press-fit onto
the cylindrical portion of the slinger. A standing portion extends
radially outward from the inner cylindrical portion. An outer cylindrical
portion extends from the standing portion. The outer cylindrical portion
has a slightly larger diameter than the larger diameter portion of the
inner ring. The magnetic encoder is adhered to the outer cylindrical
portion of the supporting member. The magnetic encoder is formed from an
elastomer mingled with magnetic powder and has N and S poles alternately
arranged along its circumference. The magnetic encoder is arranged
opposite to the wheel speed sensor via a radial gap relative to the inner
cylindrical portion of the metal core without contacting it. This makes
it possible to assure stable detecting accuracy with the signals being
strengthened by the ferromagnetic supporting member. Additionally, the
pulser ring is prevented from being soiled by rainwater or dusts.

[0029]The metal core is made of austenitic stainless steel. This improves
the detecting accuracy without exerting undesirable effects onto the
detecting sensitivity of the wheel speed sensor.

[0030]The supporting member is press-formed from ferromagnetic steel
plate. The magnetic encoder is formed from an elastomer mingled with
magnetic powder. The magnetic encoder has N and S poles alternately
arranged along its circumference. This makes it possible to assure stable
detecting accuracy while the signals are strengthened by the
ferromagnetic supporting member.

[0031]A disc shaped cover is arranged at the inner side of the sensor
holder. The inner circumference of the disc shaped cover is arranged
opposite to the outer circumference of the shoulder of an outer joint
member, via a small radial gap, to form a labyrinth seal. Drains are
formed on or near the inner circumference of the disc shaped cover. This
prevents entry of muddy water by the disc shaped cover even though the
wheel bearing apparatus is used under severe circumstances, such as muddy
water splashes. The cover enables discharge through the drain once muddy
water has entered. Accordingly, it is possible to prevent the generation
of solidification of muddy water on the slide-contacting portion of the
seal. Thus, abnormal wear of the sealing member is prevented so that
sealability and reliability of the bearing apparatus can be assured for a
long term.

[0032]The drains are circular apertures formed equidistantly along the
inner circumference of the disc shaped cover. Alternatively, the drains
are notches formed equidistantly along the inner circumference of the
disc shaped cover. The drains formed as circular apertures or notches can
prevent solidification of muddy water on the outer circumference of the
shoulder of the outer joint member.

[0033]A diameter φA of the inner circumference of the disc shaped
cover is set within a range of φB+D≦φA≦φC-D;
wherein φB is an outer diameter of the shoulder of the outer joint
member; φC is an outer diameter of the slinger; and D is an axial gap
between the disc shaped cover and the slinger. This prevents entry of
muddy water by the disc shaped cover even though the wheel bearing
apparatus is used under severe circumstances, such as muddy water
splashes. Thus, this assures desirable sealability and speed detection
for a long term.

[0034]The shoulder is abutted against a larger end face of the inner ring.
The outer diameter of the shoulder is set smaller than that of the inner
ring. An elastic lip is integrally adhered to the slinger and contacts
the end face of the inner ring. This prevents rainwater or muddy water
from entering inside of the wheel bearing apparatus through fitting
portions between the slinger and the inner ring.

[0035]The slinger and the disc shaped cover are press-formed from a steel
plate that has preserving ability. This assures stable sealability for a
long term.

[0036]The minimum anti-pull out force of the sensor holder relative to the
outer member is defined by a formula Fmin=m×a; wherein "m" is mass
of the sensor holder; and "a" is a vibration acceleration. The anti-pull
out force of the sensor holder is set at Fmin or more. This assures the
anti-pull out force of the sensor holder, to improve the sealability of
the fitting portions and the seal, and to improve the accuracy detection
and reliability.

[0037]A connector portion is integrally formed with a portion of the
sensor holder to mount a harness connecting a control mechanism mounted
on a body of a vehicle. An output signal from the magnet sensor can be
sent to the control means via a plug inserted into the connector portion.
The anti-pull out force of the sensor holder relative to the connector
portion and the plug and relative to the outer member is set larger than
the self-weight of the wheel bearing apparatus. During mounting of the
wheel bearing apparatus to a vehicle, after the sensor holder has been
mounted on the outer member, even though the wheel bearing apparatus
might be erroneously handled and hung from the connector portion via the
harness, the plug will never drop off from the connector portion. Thus,
this improves the sealability of the fitting portions and the seal and
improves the accuracy detection and reliability.

[0038]The connector portion is formed with a locking projection projecting
axially from the wheel bearing apparatus. The locking projection is
formed with an inclination tapered toward a plug inserting direction.
Thus, the locking projection can be fit into a recess formed in the plug
and locked therein. This simplifies assembling works of the wheel bearing
apparatus and assures the anti-pull out force of the connector portion
and the plug.

[0039]The fitting interface between the outer member and the metal core
can be adjusted, based on the anti-pull out force of the sensor holder.
This makes it possible to obtain a desirable fitting force without
strictly controlling the surface roughness and dimension accuracy and
suppresses an increase in machining and management steps.

[0040]The metal core includes an outer cylindrical portion press-fit into
the end portion of the outer member. A standing portion extends radially
inward from the inner side end of the outer cylindrical portion. An inner
cylindrical portion axially extends toward the outer side from the
standing portion. A radially inner portion extends radially inward from
the inner cylindrical portion. The sensor holder is integrated with the
metal core. It is insert molded in a region including the outer
cylindrical portion, the standing portion and the inner cylindrical
portion. The sealing member is adhered to the radially inner portion and
arranged with being retracted to the inner side from the detecting
portion of the wheel speed sensor. This makes it possible to arrange the
detecting portion of the wheel speed sensor and the magnetic encoder so
that they are magnetically directly opposed toward each other without
interposing any steel metal core between the two. Accordingly, it is
possible to set the air gap between them as small as possible and thus
improve the detecting accuracy and reliability.

[0041]The magnetic encoder is formed from an elastomer such as rubber
mingled with magnetic powder. The magnetic encoder has N and S poles
alternately arranged along its circumference. The wheel speed sensor
includes a magnetic detecting element, varying its characteristics in
accordance with the flow direction of the magnetic flux, and an IC. The
IC is incorporated, via a lead wire, with a wave forming circuit for
rectifying the output wave form of the magnetic detecting element. An
aperture, allowing passage of the lead wire, is formed in the outer
cylindrical portion of the metal core. This makes it possible to connect
the magnetic detecting element and the IC at a minimum distance without
the necessity of wiring the leads by passing the metal core. Thus, this
improves the reliability of the wheel speed sensor.

[0042]A plurality of the apertures are formed in the outer cylindrical
portion of the metal core. This makes it possible to efficiently perform
the wiring operation. Also, it assures the integrality between the resin
sensor holder and the metal core. Thus, this prevents separation of the
insert molded sensor holder from the metal core even though the wheel
bearing apparatus is used under severe circumstances, such as splashes of
muddy or salty water or repeat high and low temperatures.

[0043]The sensor holder is formed of non-magnetic synthetic resin. This
further improves the detecting accuracy and reliability of the wheel
speed sensor.

[0044]An annular groove is formed on the inner circumferential surface at
the inner side end of the outer member. A radially outwardly deformed
engaging portion is formed at the outer side end of the outer cylindrical
portion of the metal core so that it is fit into the annular groove. This
prevents displacement of the metal core relative to the outer member even
though vibration or shock is applied to the wheel bearing apparatus
during running of a vehicle. Thus, this prevents relative displacement of
the detecting portions to maintain stable detecting accuracy for a long
term.

[0045]The wheel bearing apparatus incorporating a wheel speed detecting
apparatus comprises an outer member integrally formed with a body
mounting flange on its outer circumference. The body mounting flange is
to be mounted on a suspension apparatus of a vehicle. The outer member
inner circumference includes double row outer raceway surfaces. An inner
member includes a wheel hub and at least one inner ring. The wheel hub
has at one end, an integrally formed wheel mounting flange. The wheel hub
outer circumference includes an inner raceway surface. A cylindrical
portion axially extends from the inner raceway surface. The inner ring is
fit onto the cylindrical portion of the wheel hub. The inner ring is
formed with the other inner raceway surface on its outer circumference.
The inner raceway surfaces are arranged opposite to the double row outer
raceway surfaces. Double row rolling elements are freely rollably
contained between the inner and outer raceway surfaces, respectively, of
the inner member and the outer member. Seals are mounted in annular
openings formed between the outer member and the inner member. A sensor
holder is injection molded from synthetic resin and includes an embedded
wheel speed detecting sensor. The sensor holder is mounted on an inner
side end of the outer member. The inner side seal of the seals includes
an annular sealing plate, a slinger and a pulser ring. The slinger has a
substantially L-shaped cross-section and is mounted onto the outer
circumference of the inner ring. The pulser ring is fit onto the outer
circumference of the slinger. The pulser ring has a magnetic encoder. The
magnetic encoder circumferential characteristics alternately and
equidistantly change. The sealing plate includes a metal core press
formed from a steel plate. The sealing plate is insert-molded into the
sensor holder and has an exposed portion of the metal core fit into the
end portion of the outer member. A sealing member is integrally bonded to
the metal core. The sealing member has integrally formed side lips and
radial lips. The side lips of the sealing member are in sliding contact
with the slinger and/or the pulser ring. The magnetic encoder and a wheel
speed sensor are arranged opposite to each other via a radial gap. An
anchoring portion is integrally formed with the metal core. The sensor
holder is integrally molded with the metal core. Synthetic resin, forming
the sensor holder, surrounds the anchoring portion. Thus, it is possible
to assure the adhessiveness or integration between the plastic resin
sensor holder and the metal core even though the wheel bearing apparatus
is used under severe running circumstances subjected to splashes of muddy
water or salty water or repeated high and low temperatures. Accordingly,
it is possible to provide a wheel bearing apparatus incorporating a wheel
speed detecting apparatus that prevents separation between the plastic
resin sensor holder and the metal core for a long term. Also, it prevents
detraction of the detecting accuracy caused by the separation between the
sensor holder and the metal core.

[0046]A wheel bearing apparatus incorporating a wheel speed detecting
apparatus comprises an outer member integrally formed with a body
mounting flange on its outer circumference. The body mounting flange is
to be mounted on a suspension apparatus of a vehicle. The outer member
inner circumference has double row outer raceway surfaces. An inner
member includes a wheel hub and an inner ring. The wheel hub has, at one
end, an integrally formed wheel mounting flange. The wheel hub outer
circumference includes an inner raceway surface. A cylindrical portion
axially extends from the inner raceway surface. The inner ring is fit
onto the cylindrical portion of the wheel hub. The inner ring is formed
with the other inner raceway surface on its outer circumference. The
other inner raceway surface is arranged opposite to the double row outer
raceway surfaces. Double row rolling elements are freely rollably
contained between the inner and outer raceway surfaces, respectively, of
the inner member and the outer member. Seals are mounted in annular
openings formed between the outer member and the inner member. A sensor
holder is injection molded from synthetic resin and has an embedded wheel
speed detecting sensor. The sensor holder is mounted on an inner side end
of the outer member. The inner side seal of the seals includes an annular
sealing plate, a slinger and a pulser ring. The slinger has a
substantially L-shaped cross-section and is mounted onto the outer
circumference of the inner ring. The pulser ring is fit onto the outer
circumference of the slinger. The sealing plate includes a metal core
press formed from a steel plate. The sealing plate is insert-molded into
the sensor holder. The sealing plate has an outer cylindrical portion
with an exposed portion fit into the end portion of the outer portion. A
standing portion extends radially inward from the outer cylindrical
portion. An inner cylindrical portion axially extends toward the inner
side. A radially inner portion extends radially inward from the inner
cylindrical portion. A sealing member is integrally bonded to the metal
core. The sealing member has integrally formed side lips and radial lips.
The slinger includes a cylindrical portion press-fit onto a smaller
diameter portion of the inner ring. A standing portion extends radially
outward from the cylindrical portion. The pulser ring is press-fit onto
the cylindrical portion of the slinger. The magnetic encoder is adhered
to the outer cylindrical portion of the pulser ring. The magnetic encoder
is formed from an elastomer mingled with magnetic powder. The encoder has
N and S poles alternately arranged along its circumference. The encoder
is arranged opposite to the wheel speed sensor via a radial gap relative
to the inner cylindrical portion of the metal core without contacting it.
The side lips of the sealing member are in sliding-contact with the
slinger. The radial lips are in contact with the pulser ring. A radially
outwardly deformed anchoring portion, including a tongue, is formed at
the outer side end of the outer cylindrical portion of the metal core.
Synthetic resin, forming the sensor holder, is molded so that it
surrounds the anchoring portion.

[0047]Further areas of applicability will become apparent from the
description provided herein. The description and specific examples in
this summary are intended for purposes of illustration only and are not
intended to limit the scope of the present disclosure.

DRAWINGS

[0048]The drawings described herein are for illustrative purposes only of
selected embodiments and not all possible implementations, and are not
intended to limit the scope of the present disclosure.

[0049]FIG. 1 is a longitudinal section view of a first embodiment of a
wheel bearing apparatus incorporating a wheel speed detecting apparatus.

[0050]FIG. 2 is a partially enlarged view of FIG. 1.

[0051]FIG. 3(a) is a cross-sectional view of a sealing plate.

[0052]FIG. 3(b) is a cross-sectional view of a modification of FIG. 3(a).

[0053]FIG. 4 is a partially enlarged view of a second embodiment of a
wheel bearing apparatus incorporating a wheel speed detecting apparatus.

[0054]FIG. 5 is a cross-sectional view of a sealing plate of FIG. 4.

[0055]FIG. 6 is a partially enlarged view of a modification of FIG. 4.

[0056]FIG. 7 is a longitudinal section view of a third embodiment of a
wheel bearing apparatus incorporating a wheel speed detecting apparatus.

[0057]FIG. 8 is a partially enlarged view of FIG. 7.

[0058]FIG. 9(a) is a perspective view of a disc shaped cover of FIG. 8.

[0059]FIG. 9(b) is a perspective view of a modification of FIG. 9(a).

[0060]FIG. 10 is a partially enlarged view of a fourth embodiment of a
wheel bearing apparatus incorporating a wheel speed detecting apparatus.

[0061]FIG. 11 is an enlarged view of a region near the disc shaped cover.

[0062]FIG. 12 is an explanatory view of a pull out condition of the sensor
holder of FIG. 10.

[0063]FIG. 13 is a partially enlarged view of a fifth embodiment of a
wheel bearing apparatus incorporating a wheel speed detecting apparatus.

[0064]FIG. 14(a) is a cross-sectional view of a sealing plate of FIG. 13.

[0065]FIG. 14(b) is a cross-sectional view of a modification of FIG.
14(a).

[0068]Preferred embodiments of the present disclosure will be hereinafter
described with reference to the drawings.

[0069]FIG. 1 is a longitudinal section view of a first embodiment of a
wheel bearing apparatus incorporating a wheel speed detecting apparatus.
FIG. 2 is a partially enlarged view of FIG. 1. FIG. 3(a) is a
cross-sectional view of a sealing plate. FIG. 3(b) is a cross-sectional
view of a modification of FIG. 3(a). In the description below, an outer
side of a wheel bearing apparatus when it is mounted on a vehicle is
referred to as the "outer side" (a left side in FIG. 1) and an inner side
of a wheel bearing apparatus is referred to as the "inner side" (a right
side in FIG. 1).

[0070]The wheel bearing apparatus incorporating a wheel speed detecting
apparatus is a third generation type for a driving wheel. It is formed as
a unit of a wheel hub 1, a double row rolling bearing 2 and a constant
velocity universal joint 8. The double row rolling bearing 2 includes an
outer member 3, an inner member 4 and double row rolling elements (balls)
5, 5.

[0071]The outer member 3 is made of medium/high carbon steel including
carbon of 0.40˜0.80% by weight such as S53C. It is formed on its
outer circumference with a body mounting flange 3b that is to be mounted
on a knuckle (not shown) to form a suspension apparatus of a vehicle. Its
inner circumference includes double row outer raceway surfaces 3a, 3a.
The double row outer raceway surfaces 3a, 3a are hardened by high
frequency induction quenching to have a surface hardness of 58˜64
HRC.

[0072]The inner member 4 includes the wheel hub 1 and an inner ring 6
secured on the wheel hub 1. The wheel hub 1 is integrally formed with a
wheel mounting flange 7 at one end. The wheel hub outer circumference
includes one (outer side) inner raceway surface 1a that opposes the
double row outer raceway surfaces 3a, 3a. A cylindrical portion 1b
extends from the inner raceway surface 1a. The wheel hub inner
circumference includes a serration (or spline) 1c for torque
transmission. Hub bolts 7a are equidistantly arranged on the wheel
mounting flange 7 along its periphery.

[0073]The wheel hub 1 is made of medium/high carbon steel including carbon
of 0.40˜80% by weight such as S53C. The wheel hub 1 is hardened by
high frequency induction quenching. The inner raceway surface 1a and a
region from a base 7b of the wheel mounting flange 7, forming a seal land
for the outer side seal 10, including the inner raceway surface 1a to the
cylindrical portion 1b has a hardness of 58˜64 HRC. A caulking
portion 1d, described later, is not quenched and remains as is having a
surface hardness after forging.

[0074]The inner ring 6 is formed on its outer circumference with another
(inner side) inner raceway surface 6a corresponding to the other (i.e.
inner side) outer raceway surface 3a. The inner ring 6 is fit onto the
cylindrical portion 1b, via a predetermined interface. The inner ring 6
is axially secured relative to the wheel hub 1 by the caulked portion 1d.
The caulked portion 1d is formed by plastically deforming the end of the
cylindrical portion 1b radially outward. The inner ring 6 and the rolling
elements 5 are made of high carbon chrome steel such as SUJ2. They are
hardened to their core by dip quenching to have a surface hardness of
58˜64 HRC.

[0075]The double row rolling elements 5, 5 are contained between the
double row outer raceway surfaces 3a, 3a of the outer member 3 and the
inner raceway surface 1a of the wheel hub 1 and the inner raceway surface
6a of the inner ring 6. The inner raceway surfaces 1a, 6a opposes the
double row outer raceway surfaces 3a, 3a. The rolling elements are
rollably held by cages 9, 9. An end face of a smaller diameter side of
the inner ring 6 abuts against a shoulder of the wheel hub 1 and forms a
double row angular contact ball bearing of a so-called back-to-back
duplex bearing type. Seals 10, 11 are mounted in annular openings formed
between the outer member 3 and the inner member 4 to prevent leakage of
lubricating grease sealed in the bearing and the entry of rainwater or
dusts into the bearing from the outside.

[0076]The constant velocity universal joint 8 includes an outer joint
member 12, a joint inner ring 13, a cage 14 and torque transmitting balls
15. The outer joint member 12 is integrally formed by a cup-shaped mouth
portion 16, a shoulder 17, that forms a bottom of the mouth portion 16,
and a shaft portion 18 that axially extends from the shoulder 17. The
shaft portion 18 is formed with a serration (or spline) 18 on its outer
circumference. The serration (or spline) 18a engages the serration 1c of
the wheel hub 1. An outer screw thread 18b is on the end of the serration
18a. The outer joint member 12 is inserted into the wheel hub via the
serrations 1c, 18a until the end face of the caulked portion 1d abuts
shoulder 17 of the outer joint member 12. Accordingly, the wheel hub 1
and the outer joint member 12 can be torque transmittably and detachably
united by a securing nut 19.

[0077]A sensor holder 20, forming part of the wheel speed detecting
apparatus, is mounted on the inner side end of the outer member 3. The
inner side seal 11 is mounted in an annular opening formed between the
sensor holder 20 and the inner ring 6. As shown in FIG. 2, the seal 11
includes an annular sealing plate 21, having a substantially L-shaped
cross-section, and a slinger 22. The sealing plate 21 and slinger 22 are
arranged opposite to each other. A pulser ring 23 is fit onto the slinger
22.

[0078]The sealing plate 21 includes a metal core 24 and a sealing member
25 integrally bonded to the metal core 24, via vulcanized adhesion. The
metal core 24 is press-formed from an austenitic stainless steel sheet
(JIS SUS 304 etc.) or a preserved cold rolled sheet (JIS SPCC etc.). As
shown in FIG. 3(a), the metal core 24 includes an outer cylindrical
portion 24a, a standing portion 24b, an inner cylindrical portion 24c,
and a radially inner portion 24d. The inner cylindrical portion 24c
extends axially from the outer cylindrical portion 24a via the standing
portion 24b. The radially inner portion 24d extends radially inward from
the inner cylindrical portion 24c. The outer cylindrical portion 24a is
formed to project from the end of the outer member 3. A sensor holder 20,
described below, is insert molded with the outer cylindrical portion 24a
and integrated with the metal core 24. The metal core 24 is preferably
made of an austenitic stainless steel sheet. Thus, it does not have
undesirable effects on the detecting sensitivity of a wheel speed sensor
29, described below.

[0079]The sealing member 25 is formed of elastic member such as synthetic
rubber. It is integrally adhered to the radially inner portion 24d of the
metal core via vulcanized adhesion. The sealing member 25 includes side
lips 25a, 25b and a pair of radial lips 25c, 25d. The side lips 25a, 25b
extend on either side of the radially inner portion 24d of the metal core
24. The pair of radial lips 25c, 25d is arranged on an inner
circumference of the radially inner portion 24d.

[0080]The slinger 22 is press-formed from an austenitic stainless steel
sheet (JIS SUS 304 etc.) or a preserved cold rolled sheet (JIS SPCC
etc.). The slinger includes a cylindrical portion 22a and a standing
portion 22b. The cylindrical portion 22a is fit onto a smaller diameter
portion of the inner ring 6. The standing portion 22b extends radially
outward from the cylindrical portion 22a. An elastic lip 26 is integrally
adhered to the slinger 22. The elastic lip 26 is in sliding-contact with
the end face of the inner ring 6. The elastic lip 26 prevents entry of
liquid such as rainwater into the inside of the bearing apparatus.

[0081]The pulser ring 23 includes a supporting member 27 and a magnetic
encoder 28. The supporting member 27 is press-fit onto the slinger 22.
The magnetic encoder 28 is integrally bonded to the outer cylindrical
portion of the supporting member 27 via vulcanized adhesion. The
supporting member 27 is press-formed from a ferromagnetic steel plate
such as ferritic stainless steel sheet (JIS SUS 430 etc.) or preserved
cold rolled sheet (JIS SPCC etc.). The supporting member 27 includes a
radially inner portion 27a, a standing portion 27b and an outer
cylindrical portion 27c. The radially inner portion 27a is press-fit onto
the cylindrical portion 22a of the slinger 22. The standing portion 27b
extends radially outward from the radially inner portion 27a. The outer
cylindrical portion 27c axially extends from the standing portion 27b
toward the outer side direction. The outer cylindrical portion 27c has a
slightly larger diameter than that of the larger diameter portion 6c of
the inner ring 6. The side lips 25a, 25b of the sealing member 25 are in
sliding-contact with the standing portions 22b, 27b, respectively, of the
slinger 22 and the supporting member 27. The pair of radial lips 25c, 25d
are in sliding-contact with the cylindrical portion 27a of the sealing
member 27.

[0082]The magnetic encoder 28 is a rubber magnet formed from an elastomer
mingled with magnetic powder such as ferrite. It is constructed as a
rotary encoder to detect wheel speed. It has N and S poles alternately
arranged along its circumference. The magnetic encoder 28 is arranged
opposite to the wheel speed sensor 29, via a radial gap (air gap)
relative to the inner cylindrical portion 24c of the metal core 24
without contacting it. This enables detecting sensitivity in cooperation
with the ferromagnetic supporting member 27 to assure stable detecting
accuracy. In addition, such a structure of the seal 11 improves
sealability and prevents the pulser ring 23 from being soiled by
rainwater or dusts.

[0083]The sensor holder 20 is made of non-magnetic resin such as
polyphenylene sulfide (PPS). A wheel speed detecting sensor 29 is
embedded in the resin. The sensor 29 is adapted to be arranged opposite
to the magnetic encoder 28, via a predetermined radial air gap. The wheel
speed sensor 29 includes a magnetic detecting element, such as a Hall
element, a magnetic resistance element (MR element) etc. for changing
characteristics in accordance with the flowing direction of magnetic
flux, and an IC. The IC is incorporated with a waveform shaping circuit
to shape the output waveform of the magnetic detecting element. This
enables wheel speed detection at low cost and high reliability. The
sensor holder 20 may be formed of injection moldable synthetic resin e.g.
PA (polyamide) 66 or polybutylene terephthalate (PBT) other than PPS.

[0084]The sensor holder 20 is arranged opposite to the end face of the
outer member 3 via a slight axial gap. The sensor holder 20 includes an
annular recess 30 so as to expose a portion of the outer circumference of
the outer cylindrical portion 24a of the metal core 24. An O-ring 31 is
elastically mounted within the recess 30. A disc shaped cover 32 is
mounted on the inner side end face of the sensor holder 20. The cover 32
includes a central aperture having a smaller diameter than an outer
diameter of the slinger 22.

[0085]The entire structure of the wheel speed detecting apparatus,
including the O-ring 31, can be previously assembled by press-fitting the
slinger 22 into the supporting member 27 of the pulser ring 23 after the
sealing plate 21 and the pulser ring 23 have been combined. The outer
cylindrical portion 24a of the metal core 24 can be fit into the end of
the outer member 3. The cylindrical portion 22a of the slinger 22 can be
press-fit onto the smaller diameter portion 6b of the inner ring 6, by
axially pushing the entire previously prepared assembly.

[0086]Although it is shown in the illustrated embodiment as an active type
wheel speed detecting apparatus including the magnetic encoder 28 and the
wheel speed sensor 29, with magnetic detecting elements such as Hall
effect elements, it is possible to use a passive type wheel speed
detecting apparatus including a magnetic encoder, a magnet, annular coil
etc.

[0087]An anchoring portion 33 is formed on the outer cylindrical portion
24a of the metal core 24 forming the sealing plate 21. In this
embodiment, the anchoring portion 33 is formed as a tongue. It is formed
by radially outwardly bending the end portion of the outer cylindrical
portion 24a. Thus, it is possible to assure the adhessiveness or
integration between the plastic resin sensor holder and the metal core
even though the wheel bearing apparatus is used under severe running
circumstances subjected to splashes of muddy water, salty water or
repeated high and low temperatures. Accordingly, it is possible to
provide a wheel bearing apparatus incorporating a wheel speed detecting
apparatus that prevents separation between the sensor holder 20 and the
metal core 24 for a long term. Also, it prevents detraction of the
detecting accuracy caused by the separation between the sensor holder 20
and the metal core 24.

[0088]The anchoring portion of the metal core 24 is not limited to the
anchoring portion 33 shown in FIGS. 2 and 3(a). It can be formed as a
circular aperture 35 shown in FIG. 3(b). Similarly to the metal core 24
previously described, this metal core 34 is press-formed of an austenitic
stainless steel sheet (JIS SUS 304 etc.) or a preserved cold rolled sheet
(JIS SPCC etc.). It has an outer cylindrical portion 34a, a standing
portion 24, an inner cylindrical portion 24c and a radially inner portion
24d. The outer cylindrical portion 34a is fit into the end portion of the
outer member 3. The inner cylindrical portion 24c extends axially from
the outer cylindrical portion 34a via a standing portion 24b. The
radially inner portion 24d extends radially inward from the inner
cylindrical portion 24c. The outer cylindrical portion 34a is formed to
project from the end of the outer member 3. A sensor holder 20 is insert
molded with the outer cylindrical portion 34a to be integrated with the
metal core 34. A plurality of circular apertures 35 are formed along the
circumferential direction of the outer cylindrical portion 34a. Synthetic
resin, forming the sensor holder 20, flows in the apertures 35 of the
metal core 34. Thus, it is possible to surely prevent separation of the
sensor holder 20 and the metal core 34 for a long term.

[0089]FIG. 4 is a partially enlarged view of a second embodiment of a
wheel bearing apparatus incorporating a wheel speed detecting apparatus.
FIG. 5 is cross-sectional view of a sealing plate of FIG. 4. FIG. 6 is a
partially enlarged view of a modification of FIG. 4. This embodiment is
different from the first embodiment (FIG. 2) only in a structure of the
metal core. Accordingly, the same reference numerals are used in this
embodiment to identify parts or portions having the same functions as
those of the first embodiment.

[0090]A sensor holder 36 is mounted on the inner side end of the outer
member 3. The inner side seal 37 is mounted in an annular opening formed
between the sensor holder 36 and the inner ring 6. The seal 37 includes
an annular sealing plate 38, having a substantially L-shaped
cross-section, and a slinger 22. The plate 38 and slinger 22 are arranged
opposite to each other. A pulser ring 23 is fit onto the slinger 22.

[0091]The sealing plate 38 includes a metal core 39 and a sealing member
25 integrally bonded to the metal core 39 via vulcanized adhesion. The
metal core 39 is press-formed of an austenitic stainless steel sheet (JIS
SUS 304 etc.) or a preserved cold rolled sheet (JIS SPCC etc.). As shown
in FIG. 5, the metal core 39 includes an outer cylindrical portion 39a,
an inner cylindrical portion 24c, a standing portion 24b and a radially
inner portion 24d. The inner cylindrical portion 24c extends axially from
the outer cylindrical portion 39a via the standing portion 39b. The
radially inner portion 24d extends radially inward from the inner
cylindrical portion 24c. A sensor holder 36, described below, is insert
molded into a region including the outer cylindrical portion 39a and the
inner cylindrical portion 24c to integrate it with the metal core 39. The
metal core 39 is preferably made of an austenitic stainless steel sheet
so that it does not undesirably effect the detecting sensitivity of the
wheel speed sensor 29.

[0092]The sensor holder 36 is made of non-magnetic resin such as
polyphenylene sulfide. A wheel speed detecting sensor 29 is embedded in
the resin. The sensor 29 is adapted to be arranged opposite to the
magnetic encoder 28, via a predetermined radial air gap. The sensor
holder 36 may be formed of injection moldable synthetic resin e.g. PA 66
or polybutylene terephthalate other than resin material described above.

[0093]The sensor holder 36 is arranged opposite to the end face of the
outer member 3 via a slight axial gap. It is formed with an annular
recess 30 so as to expose a portion of the outer circumference of the
outer cylindrical portion 39a of the metal core 39. An O-ring 31 is
elastically mounted within the recess 30. A disc shaped cover 32 is
mounted on the inner side end face of the sensor holder 36. The disc
shaped cover 32 includes a central aperture having a smaller diameter
than an outer diameter of the slinger 22.

[0094]The entire structure of the wheel speed detecting apparatus
including the O-ring 31 can be previously assembled. The slinger 22 is
press fit into the supporting member 27 of the pulser ring 23 after the
sealing plate 38 and the pulser ring 23 have been combined. The outer
cylindrical portion 39a of the metal core 39 can be fit into the end of
the outer member 3. The cylindrical portion 22a of the slinger 22 can be
press-fit onto the smaller diameter portion 6b of the inner ring 6 by
axially pushing the entire previously prepared assembly.

[0095]An anchoring portion 40 is formed on the standing portion 39b of the
metal core 39 forming the sealing plate 38. In this embodiment, since the
anchoring portion 40 is formed by a plurality of circular apertures along
the circumference of the standing portion 39b, the plastic resin of the
sensor holder 36 flows into the circular apertures forming the anchoring
portion. Thus, it is possible to assure the adhessiveness or integration
between the plastic resin sensor holder and the metal core 39 even though
the wheel bearing apparatus is used under severe running circumstances
subjected to splashes of muddy water or salty water or repeated of high
and low temperature. Accordingly, it is possible to provide a wheel
bearing apparatus incorporating a wheel speed detecting apparatus that
prevents separation between the sensor holder 36 and the metal core 39
for long term. Also, it prevents detraction of the detecting accuracy
caused by the separation between the sensor holder 36 and the metal core
39.

[0096]The anchoring portion 40 of the metal core 39 is not limited to the
structure shown in FIGS. 4 and 5. It can be formed as a structure shown
in FIG. 6. Similarly to the metal core 39 previously described, this
metal core 41 is press-formed of an austenitic stainless steel sheet (JIS
SUS 304 etc.) or a preserved cold rolled sheet (JIS SPCC etc.). It
includes an outer cylindrical portion 39a fit into the end portion of the
outer member 3. An inner cylindrical portion 41a extends axially from the
outer cylindrical portion 39a, via a standing portion 24b. A radially
inner portion 24d extends radially inward from the inner cylindrical
portion 41a. The outer cylindrical portion 39a is formed to project from
the end of the outer member 3. A sensor holder 36 is insert molded with a
region including the outer cylindrical portion 39a, the standing portion
and the inner cylindrical portion 41a to be integrated with the metal
core 41. An anchoring portion 42, comprising a plurality of circular
apertures, is formed along the circumferential direction of the inner
cylindrical portion 41a. Synthetic resin, forming the sensor holder 36,
flows in the anchoring portion 42 or apertures of the metal core 41.
Thus, it is possible to surely prevent separation of the sensor holder 36
and the metal core 41 for a long term.

[0097]FIG. 7 is a longitudinal section view of a third embodiment of a
wheel bearing apparatus incorporating a wheel speed detecting apparatus.
FIG. 8 is a partially enlarged view of FIG. 7. FIG. 9(a) is a perspective
view of a disc shaped cover of FIG. 8. FIG. 9(b) is a perspective view of
a modification of FIG. 9(a). This embodiment is different from the first
embodiment (FIG. 1) only in a partial structure of the inner member and a
structure of the disc shaped cover. Accordingly, the same reference
numerals are used in this embodiment to identify parts or portions having
the same functions as those of the first embodiment.

[0098]The wheel bearing apparatus incorporating a wheel speed detecting
apparatus is a third generation type for a driving wheel and is formed as
a unit of a wheel hub 1', a double row rolling bearing 2' and a constant
velocity universal joint 8. The double row rolling bearing 2' includes an
outer member 3, an inner member 4' and double row rolling elements 5, 5.

[0099]The inner member 4' includes the wheel hub 1' and an inner ring 6
secured on the wheel hub 1'. The wheel hub 1' is integrally formed with a
wheel mounting flange 7 at one end. The wheel hub outer circumference
includes one (outer side) inner raceway surface 1a. A cylindrical portion
1b extends from the inner raceway surface 1a. The wheel hub inner
circumference includes, a serration (or spline) 1c for torque
transmission.

[0100]The wheel hub 1' is made of medium/high carbon steel including
carbon of 0.40˜0.80% by weight such as S53C. It is hardened by high
frequency induction quenching so that the inner raceway surface 1a and a
region from a base 7b of the wheel mounting flange 7, forming a seal land
of the outer side seal 10, including the inner raceway surface 1a to the
cylindrical portion 1b has a hardness of 58˜64 HRC. The inner ring
6 is formed on its outer circumference with an inner raceway surface 6a.
The inner ring 6 is press-fit onto the cylindrical portion 1b of the
wheel hub 1' via a predetermined interference.

[0101]The outer joint member 12 is inserted into the wheel hub 1' via the
serrations 1c, 18a until the shoulder 17 of the outer joint member 12
abuts against the end face of the inner ring 6. They are detachably
united with the wheel hub 1' by fastening a securing nut 19 to an outer
thread 18b.

[0102]A sensor holder 20 is mounted on the inner side end of the outer
member 3. The inner side seal 11' is mounted in an annular opening formed
between the sensor holder 20 and the inner ring 6. As shown in FIG. 8,
the seal 11' includes an annular sealing plate 21', having a
substantially L-shaped cross-section, and a slinger 22. The sealing plate
21' and the slinger 22 are arranged opposite to each other. A pulser ring
23 is fit onto the slinger 22.

[0103]The sealing plate 21' includes a metal core 24' and a sealing member
25 integrally bonded to the metal core 24' via vulcanized adhesion. The
metal core 24' is press-formed from an austenitic stainless steel sheet
(JIS SUS 304 etc.) or a preserved cold rolled sheet (JIS SPCC etc.). The
metal core 24 includes an outer cylindrical portion 39a, a standing
portion 24b, an inner cylindrical portion 24c and a radially inner
portion 24d. The inner cylindrical portion 24c extends axially from the
outer cylindrical portion 39a via the standing portion 24b. The radially
inner portion 24d extends radially inward from the inner cylindrical
portion 24c. The outer cylindrical portion 39a is formed to project from
the end of the outer member 3. The sensor holder 20 is insert molded with
the metal core 24' and integrally united with it. The metal core 24' is
preferably made of an austenitic stainless steel sheet so that it does
not undesirably effect the detecting sensitivity of a wheel speed sensor
29, described below.

[0104]The sensor holder 20 is arranged opposite to the end face of the
outer member 3 via a slight axial gap. The sensor holder 20 is formed
with an annular recess 30 so as to expose a portion of the outer
circumference of the outer cylindrical portion 39a of the metal core 24'.
An O-ring 31 is elastically mounted within the recess 30. A disc shaped
cover 43 is mounted on the inner side end face of the sensor holder 20.
The cover 43 includes a central aperture having a smaller diameter than
an outer diameter of the slinger 22.

[0105]The entire structure of the wheel speed detecting apparatus,
including the O-ring 31, can be previously assembled. The slinger 22 is
press fit into the supporting member 27 of the pulser ring 23 after the
sealing plate 21' and the pulser ring 23 have been combined. The outer
cylindrical portion 39a of the metal core 24' can be fit into the end of
the outer member 3. The cylindrical portion 22a of the slinger 22 can be
press-fit onto the smaller diameter portion 6b of the inner ring 6 by
axially pushing the entire previously prepared assembly.

[0106]A disc shaped cover 43 is press-formed of an austenitic stainless
steel sheet (JIS SUS 304 etc.) or a preserved cold rolled sheet (JIS SPCC
etc.). The cover 43 is arranged so that a labyrinth seal 44 can be formed
relative to the shoulder 17 of the outer joint member 12 via a slight
radial gap between the two. As shown in FIG. 9(a), a plurality of drains
45, each including a circular aperture, are formed equidistantly along
the inner circumference of the disc shaped cover 43. This prevents entry
of muddy water even though the wheel bearing apparatus is used under
severe circumstances such as muddy water splashes. Also, it discharges
the entered muddy water through the drain. Accordingly, it is possible to
provide a wheel bearing apparatus incorporating a wheel speed detecting
apparatus that can prevent generation of solidification of muddy water on
the slide-contacting portion of the seal. Thus, this prevents the
generation of abnormal wear on the sealing member so that sealability and
reliability of the bearing apparatus can be assured for a long term.

[0107]The disc shaped cover is not limited to that shown in FIG. 9(a). A
disc shaped cover 46, shown in FIG. 9(b), can be used. Similar to the
disc shaped cover 43, this disc shaped cover 46 is formed of an
austenitic stainless steel sheet (JIS SUS 304 etc.) or a preserved cold
rolled sheet (JIS SPCC etc.). Cover 46 is formed with a plurality of
drains 47 arranged equidistantly along the inner circumferential edge of
the cover 46. Similarly to the disc shaped cover 43, the disc shaped
cover 46 prevents entry of muddy water even though the wheel bearing
apparatus is used under severe circumstances, such as muddy water
splashes. Also, it discharges the entered muddy water through the drain.

[0108]FIG. 10 is a partially enlarged view of a fourth embodiment of a
wheel bearing apparatus incorporating a wheel speed detecting apparatus.
FIG. 11 is an enlarged view of a region near the disc shaped cover. FIG.
12 is an explanatory view of a pulling out condition of the sensor holder
of FIG. 10. This embodiment is different from the third embodiment (FIG.
8) only in a structure of the disc shaped cover. Accordingly, the same
reference numerals are used in this embodiment to identify parts or
portions having the same functions as those of the third embodiment.

[0109]In this embodiment, the sensor holder 20 is arranged opposite to the
end face of the outer member 3 via a slight axial gap. The sensor holder
20 includes an annular recess 30 so as to expose a portion of the outer
circumference of the outer cylindrical portion 39a of the metal core 24'.
An O-ring 31 is elastically mounted within the recess 30. A disc shaped
cover 48 is mounted on the inner side end face of the sensor holder 20.
The cover 48 includes a central aperture having a smaller diameter than
an outer diameter of the slinger 22.

[0110]The disc shaped cover 48 is press-formed of an austenitic stainless
steel sheet (JIS SUS 304 etc.) or a preserved cold rolled sheet (JIS SPCC
etc.). The cover 48 is arranged so that its inner circumferential edge
forms a labyrinth seal 44 relative to the shoulder 17 of the outer joint
member 12 via a slight radial gap between the two. In general, the
smaller the radial gap of the labyrinth seal, the more effective is the
sealability. However, since it is believed that the disc shaped cover 48
would interfere with a rotational member (i.e. shoulder 17 of the outer
joint member 12) if the dimensions of the related parts are not strictly
limited, the radial gap should be determined in view of the cost
effectiveness.

[0111]Positional and dimensional relations exist between the disc shaped
cover 48 and the slinger 22. A diameter φA of the inner circumference
of the disc shaped cover 48 is set within a range
φB+D≦φA≦φC-D; wherein φB is an outer
diameter of the shoulder 17 of the outer joint member 12, φC is an
outer diameter of the slinger 22, and D is an axial gap between the disc
shaped cover 48 and the slinger 22. By setting the diameter φA of the
inner circumference of the disc shaped cover 48 within the range
φB+D≦φA≦φC-D, a sufficient labyrinth effect can
be achieved even when the maximum diameter φAmax of the inner
circumference of the disc shaped cover 48 is φC-D (i.e.
φAmax=φC-D). On the other hand, the interference between the disc
shaped cover 48 and the shoulder 17 of the outer joint member 12 can be
prevented even when the minimum diameter φAmin of the inner
circumference of the disc shaped cover 48 is φB+D (i.e.
φAmin=φB+D). Accordingly desirable sealability can be effectively
assured by this disc shaped cover 48 even when the wheel bearing
apparatus is used under severe circumstances subjected not only to
rainwater or muddy water but also dusts including pebbles. Thus, it is
possible to provide a wheel bearing apparatus incorporating a wheel speed
detecting apparatus with high reliability that can stably detect wheel
speed for a long term.

[0112]In this embodiment, the force required to pull out the sensor holder
20 from the outer member 3 is determined by a predetermined formula.
Thus, the fitting interference between the outer member 3 and the metal
core 24' is adjusted in accordance with the pull out force determined by
the formula. That is, the minimum pull out force Fmin of the metal core
24' against vibration can be determined as Fmin=m×a (N); wherein
"m" (kg) is a mass of the sensor holder 20, and "a" (m/sec2) is an
acceleration. When the mass (m) of the sensor holder 20 is 0.05 kg, and
the acceleration (a) is 30 G, Fmin can be determined as
Fmin=0.05×30 G=14.7 N wherein "G" is the gravitational acceleration
(=9.80665 m/sec2).

[0113]As shown in FIG. 12 the minimum pull out force Fmin of the metal
core 24', i.e. the sensor holder 20, is calculated in accordance with
conditions of vibration previously loaded on the wheel bearing apparatus
and the mass (m) of the sensor holder 20. Accordingly, the anti-pull out
force of the sensor holder 20 can be assured without unnecessarily
limiting the surface roughness and the dimensional accuracy of the
fitting portion only by adjusting the fitting interference between the
metal core 24' and the outer member 3. The fitting interference
calculated from the pull out force determined, for example, by fitting
surface pressure, dimensions of relating parts, finished condition of the
fitting surfaces, etc. so that they can satisfy the minimum pull out
force Fmin. Thus, it is possible to suppress an increase in machining and
management steps and to provide a wheel bearing apparatus incorporating a
wheel speed detecting apparatus that improves sealability of the fitting
portion and the seal and reliability to maintain the detecting accuracy.

[0114]Although it has described above that the anti-pull out force of the
sensor holder can be assured by adjusting the fitting interference
calculated from the pull out force of the fitting interference between
the metal core 24' and the outer member 3, the anti-pull out force can be
determined by another way. That is, in this embodiment, a connector
portion 20a for mounting a harness (not shown) for connecting the wheel
speed sensor 29 and a control means (not shown) mounted on a body of
vehicle is integrally molded with an upper portion of the annular sensor
holder 20. A plug mounted on one end of a mating harness (not shown) is
connected to the connector portion 20a to send output signals from the
wheel speed sensor 29 to the control means.

[0115]The connector portion 20a is formed with a locking projection 49
that projects axially from the wheel bearing apparatus. The locking
projection 49 is formed with an inclined tapered toward a plug inserting
direction (upper side of FIG. 10) and a normal portion (lower side of
FIG. 10). On the other hand, the mating plug is formed with a recess (not
shown) for engaging the locking projection 49 so that the locking
projection 49 can be fit into a recess of the plug and locked therein.

[0116]An anti-pull out force of the plug from the connector portion 20a is
determined at a predetermined value. That is, the anti-pull out force is
determined larger than the self-weight of the wheel bearing apparatus,
preferably more than three times the self-weight of the wheel bearing
apparatus or larger than 30 kg. Thus, the plug will never drop off from
the connector portion 20a although the wheel bearing apparatus might be
erroneously handled and hung from the connector portion, via the harness,
during mounting of the wheel bearing apparatus to a vehicle after the
sensor holder has been mounted on the outer member.

[0117]The anti-pull out force of the sensor holder 20 from the outer
member 3, the anti-pull out force of the outer cylindrical portion 39a of
the metal core 24' fit into the outer member 3, may be determined larger
than the self-weight of the wheel bearing apparatus. Ordinarily, it is
more than three times the weight of the wheel bearing apparatus or larger
than 30 kg.

[0118]FIG. 13 is a partially enlarged view of a fifth embodiment of a
wheel bearing apparatus incorporating a wheel speed detecting apparatus.
FIG. 14(a) is a cross-sectional view of a sealing plate of FIG. 13. FIG.
14(b) is a cross-sectional view of a modification of FIG. 14(a). This
embodiment is different from the first embodiment (FIG. 2) only in a
structure of the metal core. Accordingly, the same reference numerals are
used in this embodiment to identify parts or portions having the same
functions as those of the first embodiment.

[0119]A sensor holder 20, forming part of the wheel speed detecting
apparatus, is mounted on the inner side end of the outer member 3. An
inner side seal 50 is mounted in an annular opening formed between the
sensor holder 20 and the inner ring 6. The seal 50 includes an annular
sealing plate 51, having a substantially L-shaped cross-section, and a
slinger 22. The plate 51 and slinger 22 are arranged opposite to each
other. A pulser ring 23 is fit onto the slinger 22.

[0120]The sealing plate 51 includes a metal core 52 and a sealing member
25 integrally bonded to the metal core 52, via vulcanized adhesion. The
metal core 52 is press-formed of an austenitic stainless steel sheet (JIS
SUS 304 etc.) or a preserved cold rolled sheet (JIS SPCC etc.). The metal
core 52, as shown in FIG. 14(a), includes an outer cylindrical portion
52a, a standing portion 52b, an inner cylindrical portion 52c and a
radially inner portion 52d. The inner cylindrical portion 52c extends
axially from the outer cylindrical portion 52a via the standing portion
52b. The radially inner portion 52d extends radially inward from the
inner cylindrical portion 52c. The sealing member 25 is adhered to the
radially inner portion 52d. The outer cylindrical portion 52a is formed
to project from the end of the outer member 3. A sensor holder 20 is
insert molded with portions of the metal core 52 including the outer
cylindrical portion 52a, the standing portion 52b and inner cylindrical
portion 52c to be integrated with it. The outer cylindrical portion 52a
is formed with a circular aperture 53 for passing a lead wire from the
wheel speed sensor 29. The circular aperture 53 is one example and other
configuration e.g. a rectangular or square may be adopted.

[0121]As described above, the metal core 52 includes the outer cylindrical
portion 52a. The standing portion 52b extends radially inward from the
inner side end of the outer cylindrical portion 52a. The inner
cylindrical portion 52c extends axially from the outer cylindrical
portion 52a toward the outer side. The radially inner portion 52d extends
radially inward from the inner cylindrical portion 52c. The sensor holder
20 is insert molded with portions of the metal core 52 including the
outer cylindrical portion 52a, the standing portion 52b and inner
cylindrical portion 52c to be integrated with it. The sealing member 25
is adhered to the radially portion 52d. The radially inner portion 52d is
arranged so that it is retracted from the magnetic detecting element
(detecting portion) 29a of the wheel speed sensor 29 toward the inner
side.

[0122]With the adoption of the metal core 52 having such a structure, the
wheel speed sensor 29 can magnetically directly oppose the magnetic
encoder 28 without any interposition of the metal core of steel plate.
Thus, it is possible to remarkably reduce the radial gap (air gap)
between the two. Accordingly, it is possible to provide a wheel bearing
apparatus incorporating a wheel speed detecting apparatus that obtains a
high flux density and improves the detection accuracy and reliability.

[0124]In this modification the outer side end of the outer cylindrical
portion 55a is bent radially outward to form an engaging portion 56. A
plurality of circular apertures 53 are formed in the outer cylindrical
portion 55a. The engaging portion 56 of the outer cylindrical portion 55a
of the metal core 55 engages an annular groove 3c formed on the inner
circumference of the end of the outer member 3. During assembly of the
sensor holder 20, into the outer member 3, the outer cylindrical portion
55a of the metal core 55 is elastically deformed. The engaging portion 56
of the metal core 55 is snapped into the annular groove 3c. Thus, the
metal core 55 is securely press-fit into the outer member 3. Accordingly,
it is possible to prevent displacement of the metal core 55 relative to
the outer member 3. Also, displacement of the detecting portion is
prevented even if vibration or shock is applied to the bearing during
running of the vehicle. Thus, this maintains stable detecting accuracy
for a long term.

[0125]In addition, the provision of the plurality of circular apertures 53
in the outer cylindrical portion of the metal core 55 makes it possible
to efficiently perform the wiring operation. Also, it assures the
integral bonding between the sensor holder 20 and the metal core 55.
Thus, this prevents separation of the insert molded sensor holder 20 from
the metal core 55 even though the wheel bearing apparatus is used under
severe circumstances including splashes of muddy or salty water or
repeated high and low temperatures.

[0126]According to this embodiment, the provision of the circular
apertures 53 for passing the lead wire 29b makes it possible to connect
the magnetic detecting element 29a and an IC 29c at a shortest distance
without bypassing the metal core. Thus, this improves the reliability of
the wheel speed sensor 29. In addition, plastic resin, forming the sensor
holder 20, flows into the apertures 53 and firmly grips the metal core 52
(55) after the IC 29c and the harness (not shown) have been connected.
Thus, it is possible to prevent separation of the insert molded sensor
holder 20 from the metal core 52 (55) for a long term even though the
wheel bearing apparatus is used under severe circumstances including
splashes of muddy or salty water or repeated high and low temperatures.

[0128]The present disclosure has been described with reference to the
preferred embodiments. Obviously, modifications and alternations will
occur to those of ordinary skill in the art upon reading and
understanding the preceding detailed description. It is intended that the
present disclosure be construed to include all such alternations and
modifications insofar as they come within the scope of the appended
claims or their equivalents.